6266-23-5Relevant articles and documents
Strong hydrogen bonds in 1:1 and 2:1 complexes of pyridine betaine with strong acids
Dega-Szafran, Zofia,Gdaniec, Maria,Grunwald-Wyspianska, Monika,Kowalczyk, Iwona,Szafran, Miroslaw
, p. 297 - 308 (1994)
The crystal structure of bis(pyridine betaine) hydrochloride-d1, monohydrate-d2 has been determined by X-ray analysis.The carboxylate groups of a pair of pyridine betaine molecules are bridged by a deuteron to form a centrosymmetric dimer featuring a very strong hydrogen bond of length 2.444(4) Angstroem.The geometric mass effect (ΔR ca. 0.008 Angstroem) is well within the range observed for this type of hydrogen bond.The FT-IR spectra of polycrystalline 1:1 and 2:1 complexes of pyridine betaine with HNO3, HCl, HBr, HI, HO3SCF3, HClO4, HBF4, and H2SO4 have been investigated in the 4000-200 cm-1 range.In the 1:1 complexes a proton is transferred from the acid to the betaine molecule, C5H5N+CH2COOH*A-, and both the νOH and νC=O frequencies vary with the proton acceptor properties of the anion.The spectra of the 2:1 complexes show broad and intense O*H*O stretching absorptions in the 1500-200 cm-1 range which are slightly affected by the anion and are similar to that for type A acid salts of carboxylic acids.The skeletal vibrations of the betaine residue were identified by second derivative spectroscopy.Evidence based on the νC=O vibration and deuteration suggests that the hydrogen bonds in +A- are described by single minimum potentials; νH = 940 cm-1, νH/νD = 1.2.As betaines are widely distributed in plants and animal tissue and form complexes with strong hydrogen bonds, such bonds should be formed in biological systems.
Valorization of chitin derived N-acetyl-D-glucosamine into high valuable N-containing 3-acetamido-5-acetylfuran using pyridinium-based ionic liquids
Zang, Hongjun,Lou, Jing,Jiao, Shuolei,Li, Huanxin,Du, Yannan,Wang, Jiao
, (2021/02/26)
Chitin and its derivatives contain biologically fixed nitrogen elements, which can provide nitrogen sources for N-containing chemicals. Herein, a series of pyridinium-based ionic liquids were synthesized to directly catalyze the conversion of N-acetyl-D-glucosamine (NAG, the monomer of chitin) to 3-acetamido-5-acetylfuran (3A5AF). The yield of 3A5AF in 1-carboxymethyl pyridinium chloride ionic liquid reached 37.49%, without any additives. Using B2O3 and CaCl2 as additives, the optimum yield increased to 67.37% at 180 °C in 20 min. In addition, HPLC-MS analysis has been utilized to elucidate the reaction mechanism. This research on turning “waste” into “wealth” opens up new ways for the utilization of biomass waste, which not only reduces environmental pollution but also has potential economic value.
Method for preparing 3-hydroxypropionaldehyde by hydrating acrolein
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Paragraph 0049, (2020/12/31)
The invention relates to a method for preparing 3-hydroxy propionaldehyde by hydrating acrolein. The acrolein is homogeneously catalyzed under the action of a N-heterocyclic carboxylic acid ionic liquid to prepare 3-hydroxy propionaldehyde, wherein the hydration reaction liquid is subjected to aqueous two-phase extraction to recover the ionic liquid catalyst for cyclic utilization. According to the invention, the method is simple to operate and stable in process, the catalyst has very high reaction activity and very good selectivity, and the problems of separation of a homogeneous catalyst andinstability and easy deactivation of a solid catalyst in the hydration process are effectively solved.